Field of the Invention
The present invention relates to information processing for measuring the shape or the position and orientation of an object in a three-dimensional space.
Description of the Related Art
Distance measurement apparatuses for measuring distance information have been proposed to measure the shape or the position and orientation of an object in a three-dimensional space. In particular, as a noncontact distance measurement apparatus, a method of measuring distance information to a measurement target object by analyzing reflected light of light that has irradiated the object is often used. For example, there is known a method of capturing, by a camera, an object on which structured light is projected and calculating distance information from the light source position, the camera position, and the pattern position on the captured image based on triangulation, such as a slit light projecting method or a space encoding method.
In many cases, the calculated distance information is handled as a range image (measured data as distance information) having the same resolution as that of the captured image or the same resolution as that of the pattern of the structured light.
When the resolution of the range image is the same as that of the captured image, the density of measurement lines on a dimension almost perpendicular to the measurement lines (an axis almost perpendicular to the measurement lines) of the structured light out of two dimensions that constitute the coordinate plane of the range image is lower than the resolution of the captured image on the corresponding dimension. Hence, the range image includes many immeasurable areas where the distance information is not calculated, and the storage capacity may be wasted to hold such range images.
Additionally, when the resolution of the range image is assumed to be the same as that of the pattern of the structured light, the resolution of the range image can be lowered, in other words, the storage capacity can be reduced. When the structured light is projected using, for example, a projector, in general, the resolution of the pattern of the structured light is lower than that of the captured image on both of the two dimensions. Hence, in the range image having the same resolution as that of the pattern of the structured light, many pieces of distance information which should be calculated are missed.